When you are starting out, you want to cast your net wide: include in your search the big bibliographic databases that cover most of the material published out there. Then you can focus your search in smaller databases if your results are not satisfying enough.
Remember that depending on the discipline, use of databases may differ; Scopus and Web of Science do not index many books, which is the cornerstone of Humanities research, while Scholar does, although the quality is disputed.
Some things you can do with indexing databases:
To learn more about the mechanics of search in Google click on the following link:
Watch the above video to learn how to search Scopus effectively